What squawk code indicates an emergency situation?

The squawk code that indicates an emergency situation is 7700. This code is universally recognized in aviation for signaling a general emergency, which can encompass any serious situation that may require assistance from air traffic control or other aircraft. When a pilot sets their transponder to 7700, it alerts air traffic control and other nearby aircraft that they are in distress and may need immediate help.

The other codes serve different specific purposes. For example, 7500 is used to indicate a hijacking or unlawful interference with the aircraft, while 7600 signifies a communication failure with air traffic control. Each of these codes plays a crucial role in the communication and management of various aviation emergencies, but 7700 specifically denotes a broad emergency that could encompass various dangerous or critical situations.